• 한국결정성장학회지
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• 제13권4호
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• pp.168-171
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• 2003

$YMnO_{3}$ single crystals have been grown by a floating zone technique and the optimal growth conditions were investigated. Their crystallinity and microstructure were characterized by the chemical etch pit patterns, their distribution and the compositional difference depending on the G value. In particular, the microstructural feature was interpreted in terms of compositional deviation along radial direction on (1010) growth plane.

• Journal of the Korean Wood Science and Technology
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• 제36권1호
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• pp.12-20
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• 2008

국내에서 성장한 주요 침엽수 3종(소나무, 잣나무, 리기다소나무)의 수간 내 셀룰로오스 상대결정화도와 결정폭에 대한 수평방향 및 수직방향 변이를 X선 회절법에 의해 조사하였다. 각 수종의 상대결정화도 평균값은 소나무 60.6%, 잣나무 61.7%, 리기다소나무 49.4%로 리기다소나무가 가장 낮게 나타났다. 공시 수종의 상대결정화도는 약 10~15연륜까지 증가하다가 그 후 거의 일정한 값을 보여 주었고 만재부의 상대결정화도가 조재부의 상대결정화도보다 다소 높게 나타나는 경향이 있었다. 소나무 상대결정화도는 수관부보다 기부에서 다소 낮게 나타났으나 잣나무, 리기다소나무는 수고에 따른 차이를 거의 나타내지 않았다. 각 수종의 셀룰로오스 결정폭은 3수종 모두 2.8~3 nm 정도로 거의 차이가 없었고 수평방향 및 수직방향, 조만재 간에도 차이가 없었다. 따라서 상대결정화도와 결정폭 중 상대결정화도는 국내산 주요 침엽수재의 미성숙재와 성숙재를 구분하는 재질 지표의 하나로 이용이 가능할 것으로 생각되었다.

• Bulletin of the Korean Chemical Society
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• 제17권10호
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• pp.925-929
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• 1996

Uranyl hydrolysis precipitates were obtained by increasing pH value of aqueous uranyl solution in the range of neutral to alkaline pH value and their phase transformation during the solubility experiment under various conditions has been examined. The precipitates formed in the hydrolysis reaction of uranyl ion had a layered structure such as a meta-schoepite phase, a schoepite structure, or a mixed phase of meta-schoepite and schoepite. Phase transformation between them was strongly dependent on the pH value at which the precipitate was formed. The distance between the layers in meta-schoepite or schoepite phase was ∼7.35 Å, and it was increased with the pH value at which the precipitate was synthesized as well as the pH values of the aqueous solution. The phase transformation from a meta-schoepite to schoepite was fast for the precipitates formed at low pH values, however, it was not the case for the precipitates formed at high pH values. A small difference of pH value in aqueous solution gave a great change on its solubilities near pH 9.7, because a layered structure of the precipitates became amorphous above that pH value. Greater solubility for the precipitate formed at higher pH value can be explained from the fact that the precipitates formed at low pH value had a better crystallinity and also that the precipitates formed at higher pH value has a slower rate of crystallization.

• 한국진공학회지
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• 제19권2호
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• pp.128-133
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• 2010

ZnO:Al 박막은 산소 압력을 조절한 두 번의 증착 과정을 이용하여, DC 펄스 마그네트론 스퍼터링 방법에 의해 증착되었다. 시드막은 다양한 Ar/$O_2$ 압력비에서 증착되었으며, 벌크막은 순수한 Ar가스를 사용하여 증착되었다. 시드막 증착시 산소 압력이 증가함에 따라, 결정성과 (002) 배향성의 정도는 증가했다. 비저항은 시드가 없는 샘플의 경우 $4.7\times10^4\Omega{\cdot}cm$ cm로부터 Ar/$O_2$ = 9/1 샘플의 경우 $3.7\times10^4\Omega{\cdot}cm$까지, 결정성의 증가와 함께 점차 감소했다. 에칭된 표면은 분화구 형상의 구조를 보여주었으며, 급격한 형상 변화가 결정성 증가와 함께 나타났다. Ar/$O_2$= 9/1 조건의 샘플은 500 nm 에서 88%의 매우 높은 haze 수치를 보여주었으며, 이는 AFM 이미지에서 보여지는 것처럼 큰 표면 구조 크기에 의해 설명된다.

• Transactions on Electrical and Electronic Materials
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• 제13권6호
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• pp.322-325
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• 2012

Crystalline silica was synthesized by annealing amorphous silica at $1,300^{\circ}C$ or $1,400^{\circ}C$ for various times, and the crystallinity was estimated by X-ray diffraction (XRD) analysis. In order to prepare a low dielectric material, epoxy/crystalline silica composites were prepared, and the effect of silica content on the dielectric properties was studied under various functions of frequency and ambient temperature. The dielectric constant decreased with increasing crystalline silica content in the epoxy composites, and it also decreased with increasing frequency. At 120 Hz, the value of 5 wt% silica decreased by 0.25 compared to that of 40 wt% silica, and at 23 kHz, the value of 5 wt% silica decreased by 0.23 compared to that of 40 wt% silica. The value increased with increasing ambient temperature.

• Corrosion Science and Technology
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• 제3권3호
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• pp.112-117
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• 2004

This work investigated the material properties of Ni-P-B alloy electrodeposits obtained from a Ni sulfamate bath as a function of the contents of the P and B sources($H_3PO_3$ and dimethyl amine borane complex(DMAB), respectively) with/without additives. Chemical composition, residual stress, microstructure and micro hardness were investigated using ICP(inductively coupled plasma) mass spectrometer, flexible strip, XRD, TEM and micro Vickers hardness tester, respectively. From the results of the compositional analysis, it was observed that P and B are incorporated competitively during the electrodeposition and the sulfur from the additive is codeposited into the electrodeposit. The measured residual stress value increased in the order of Ni, Ni-P, Ni-B and Ni-P-B electrodeposits indicating that boron affects the residual tensile stress greater than phosphorus. As the contents of the alloying element sources of P and B increased, crystallinity and the grain size of the electrodeposit decreased. The effect of boron on crystallinity and grain size was also relatively larger than the phosphorus. It can be explained that the boron with a smaller atomic radius contributes to the increase of residual stress in the tensile direction and the larger restraining force against the grain growth more significantly than the phosphorus with a larger atomic radius. Introduction of an additive into the bath retarded crystallization and grain growth, which may be attributed to the change of the grain growth kinetics induced by the additive adsorbed on the substrate and electrodeposit surfaces during electrodeposition.

• 한국자기학회지
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• 제12권4호
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• pp.132-136
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• 2002

유리기관 위에 이온 빔 증착(ion beam deposition ; IBD)법으로 제작한 버퍼층(buffer layer) Si의 두께에 따른 ［NiFe/FeMn/NiFe］3층박막의 결정성과 교환결합세기(exchange bias field ; H$_{ex}$)를 조사하였다. 버퍼층 Si는 NiFe층을 fcc(111)로 매우 우세하게 초기에 결정성장 시켰다. Si/NiFe 위의 증착된 FeMn층은 ${\gamma}$-fcc(111)구조로 성장함에 따라 안정되고 큰 H$_{ex}$를 가졌고, 버퍼 110 Oe로 거의 일정하였으며, 상부 FeMn/NiFe 이중구조의 H$_{ex}$는 300 Oe까지 증가하였다. 버퍼층이 Ta일 경우와 비교해서 Si일 때 H$_{ex}$와 결정성이 향상되었다.이 향상되었다.

• 한국광물학회지
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• 제4권1호
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• pp.32-42
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• 1991

직운산층의 열적변성도를 밝히기위해 일라이트의 '결정도'와 녹니석의 화학성분을 이용하였다. 직운산층의 일라이트 '결정도'값은 Weaver index로는 4.48에서 32.5에 이르며, Kubler index로는 $0.14{{\Delta}{\circ}}\;2{\Theta}$에서 $0.03{{\Delta}{\circ}}\;2{\Theta}$에 이른다. 대부분의 일라이트 '결정도'값은 epizone의 영역 (K. I.< $0.21{{\Delta}{\circ}}\;2{\Theta}$)에 속한다. 직운산층 녹니석에 의해 계산된 온도와 그 화학 분석치(Fe/(Fe+Mg)=0.45, Tet. Al/Octa. Al=0.84, the calculated temperature=250-270${\circ}C$)는 기존의 epizone 녹니석의 연구결과와 잘 일치한다. 이 연구의 결과는 직운산층의 변성정도가 epizone에 속하고 직운산층은 과거에 적어도 300${\circ}C$의 온도에 도달했다는 것을 나타낸다.

• 한국염색가공학회지
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• 제5권3호
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• pp.221-228
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• 1993

Cellulose acetate and methyl cellulose were synthesized from waste cellulose in order to make waste knit on value added highly. Crystal waste cellulose by oxidation using $HIO_4$ and then acetylation was decrystallized. A degee of crystallinity was measured by X-ray diffraction and the structure was identified by FT-IR spetroscopy, respectively. Cellulose acetate was prepared from the reaction of decrystallized cellulose with acetic acid, cone-$H_{2}SO_{4}$ and acetic anhydride. Also, structure identification by FT-IR and a degree of crystallinity by X-ray diffraction were performed. DS of the synthesized cellulose acetate was 2.8 and viscosity average molecular weight was 238,000. Also, methyl cellulose was synthesized by treating cellulose acetate with NaOH and iodomethane. DS of the synthesized methyl cellulose was 3.0. Glucose unit with three hydroxy groups was all substituted by methoxyl groups. It was identified by FT-IR spectroscopy. Also, the thermal properties of the synthesized methyl cellulose were examined by DSC. It shewed two shewed melting peaks at 22$0^{\circ}C$ and 24$0^{\circ}C$ in the 2nd scan. It proved that DS=3.0 of methyl cellulose was a thermotropic liquid crystal.

• 한국산업융합학회 논문집
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• 제2권1호
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• pp.27-33
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• 1999

Effects of spinning speed and draw ratio on structure and mechanical properties of PP filament. A The crystalline structure and mechanical properties of uniaxially deformed polypropylene filament has been examined by XRD, birefringence, UTM and density method. Uniaxially deformed PP filament was prepared of various spinning speeds (300, 600, 900m/min.) and draw ratio(x2, x3, x4). From the results of these studies, it found the following facts. Firstly, it was found that the crystallinity and crystallite size (110plane) of the samples were increased with increasing of spinning speed and draw ratio, especially, it was rapidly increased between as spun yarn and 2 times draw ratio. Secondly, birefringence value was increased with increasing of spinning speed and draw ratio. The mechanical properties of initial modulus, tensile strength were increased with increasing of spinning speed and draw ratio also, but the degree of elongation decreased as spinning speed and draw ratio.